2004 Dodge Ram 1500 5.7L Hemi no crank no start

All right.. here's hoping the general masses can source this problem.

2004 Dodge Ram 1500 5.7L Hemi. I've owned it for seven years +, it is not my daily drive vehicle, but has been super reliable when needed. That is until last week.

I drove it into the garage about 2-3 months ago and disconnected the battery. This is where it is usually parked over the winter on when not in use.

Last week i reconnected the battery to change out the water pump and flush the cooling system and it would not start. Starter did not engage at all. I figured the battery was low in charge.. tested it and it was.. i put the charger on it (2A setting) and re-connected. Still no crank.

What it does: ignition turns freely and all dash lights come on. The appropriate lights (radio/compass etc) all go dark when the key is turned to start.

What I've tried:
-Checked all of the fuses both visually and with a testing light. All have power on both sides, especially everything relating to starter and ignition.
-Replaced battery with a brand new one. no change.
-Pulled the starter relay and swapped it with one of the others. no change.
-Voltage tested the starter relay plug. has constant power on bottom, when ignition is set to 'on'. Has no power coming to it on the left side, when the key is turned to start.
-Crossed the relay terminals (effectively bypassing the relay) from the bottom power when ignition is 'on' to the top terminal which powers the starter solenoid. Starter engages and engine turns over freely. (no issues with starter). Truck did not start, but from what I've read this is expected.
-Removed the steering column panel and exposed wires. Checked for power. Red wire has power when ignition is set to 'on'. Yellow wire has power once the key is turned to start.
-Removed the fuse/relay box under the hood. Wiggled/checked all connections are tight. There is one wire harness with a solid yellow wire. Tested this for power (none). Tested for power when ignition to start (none).. same as starter relay terminal.
-Checked over wiring harnesses on passenger side of firewall. Wiggled. .all are tight. No signs of corrosion or wear on the connectors or the related harnesses.

Extra bits of info (may or may not be related)
- I haven;t heard the fuel pump kick in, but haven't tested for this at the relay yet either. That's going to be tonights task.
-The PRNDL indicator has a square around P when the ignition is set to "on", but the square disappears when the ignition is turned to start.
-With the ignition in the 'on' position the shifter moves freely through all of the gears and is reflected as same on the dash.
-Tried to put truck in neutral and start, and it did not make a difference.

My absolute guess in this case is that the ignition system is operating fine, but something is preventing the power going to the starter relay.. which PRNDL sensor is one of these potential causes.

How do i bypass the PRNDL sensor to test this?
What other things could be the cause of computer not letting the ignition start power get to the starter relay?
And how do i test for those?

Any help is appreciated.